In an RFID system, an RFID reader may be required to communicate with a large number of different RFID tags within a given communication range. Where each of the different RFID tags is identified by a unique identification number, it is imperative that the RFID reader be able to quickly and accurately read the identification number associated with each tag.
One major application of RFID systems is electronic inventory. In modern business, maintaining an accurate inventory of merchandise is crucial. In the past, taking inventory was an entirely manual process, and therefore slow and expensive. In an RFID electronic inventory system, an RFID tag is attached to each item to be inventoried. Each RFID tag is assigned a unique tag identification number.
In typical inventory applications, a large number of tagged items are stacked on a pallet. For example, a single pallet may have 50 boxes containing Product X and 50 boxes containing Product Y. The tags associated with Product X will have similar tag identification sequences and the tags associated with Product Y will have similar tag identification sequences. For example, Product X tag identification sequences will cluster at one section of a binary tree and Product Y tag identification sequences will cluster at a different section of a binary tree.
Existing techniques to increase read rate by capitalizing on the clustering of tags use a masking technique on the information transmitted. However, the masking technique only allows for a single sequential bit string in a tag identification sequence to be masked efficiently. Masking multiple non-sequential bit strings requires complicated mechanisms for defining the sub-masks and appending the sub-masks into a single command.
Consequently, a need exists for a technique that permits an RFID reader to efficiently read a population of RFID tags in a manner that optimally utilizes information about the tag population gained by the RFID reader, other RFID readers, or other systems compiling information for RFID readers, during or before the reading process.
A further need exists for a method of communicating between an RFID reader and a population of RFID tags that minimizes the data exchanged between a reader and tags and/or maximizes the read rate of a population of RFID tags.